1. Fields of the Invention
The present invention relates to a ratchet wrench, and more particularly, to a ratchet wrench having a driving unit with two adjustable toothed rings so as to be precisely engaged with related components.
2. Descriptions of Related Art
The conventional ratchet wrench known to applicant is disclosed in U.S. Pat. No. 6,457,386 and comprises a main body, a drive shaft, a handle, a first annular gear, a second annular gear, a drive member, a pair of first pawls, a pair of second pawls, a rotating wheel, a control member, a plurality of balls, a plurality of compression springs, and a coiled spring. The main body has a through hole to receive the drive shaft, a pair of pivot holes, a groove to receive the drive member, and a plurality of inner teeth. The through hole communicates with the groove. The drive member has a through aperture and a chamber. The handle has a blind hole to receive the drive shaft. The first annular gear has a plurality of inner periphery serrations and a plurality of one-sided serrations. The second annular gear has a plurality of inner periphery teeth and a plurality of one-sided teeth. Each of the first pawls has a plurality of positioning recesses and a plurality of outer teeth. Each of the second pawls has a plurality of periphery serrations and a plurality of one-sided serrations. The rotating wheel has an oblong center hole. The control member has a pillar and a press disk disposed on the pillar. The pillar has a plurality of circular holes, and each of the circular holes of the pillar receives the corresponding compression spring and the corresponding ball. A pair of studs pass through the pivot holes of the main body and an annular recess of the drive shaft. The chamber of the drive member receives the first pawls and the second pawls. The first annular gear encloses one of the first pawls and one of the second pawls. The second annular gear encloses the other of the first pawls and the other of the second pawls. The pillar is inserted through the coiled spring, the oblong center hole of the rotating wheel, and the through aperture of the drive member. The coiled spring is disposed between the press disk and the rotating wheel, and each of the balls engages with one of the first pawls and the second pawls.
However, the two second annular gears are not adjustable relative to the driving member so that the engagement between the beveled teeth of the drive shaft and the two second annular gears may not be perfect as expected. Each of the driving member, the second annular gears and the drive shaft has its own tolerance, if the tolerance is too big, the engagement between the beveled teeth of the drive shaft and the two second annular gears is affected. The maximum diameter of the driving member has to be matched with the inner teeth of the inner teeth so that the driving member is supported by the inner teeth. The main body and the driving member are pivotably connected to the inner teeth, the pivotable connection between the main body and the driving member will be affected. The driving member is made as a one piece and this requires higher manufacturing cost.
Another ratchet wrench is disclosed in U.S. Pat. No. 9,038,505 has similar shortcomings as those in U.S. Pat. No. 6,457,386.
The present invention intends to provide a ratchet wrench to eliminate the shortcomings mentioned above.